Insulated electrical conductor



OCV- 3, 1950 B. w. NQRDLANDER Erm. 2,524,536

I INSULTED ELECTRICAL CONDUCTOR v Filed June 13, 1945 caPPf/ an coppa?naar COPPER 0f? 00P/CEI? LOV Their* Attorney Patented oa. a, i9502,524,536

UNITED sTaTEs PATENT ori-ICE INSULATED ELECTRICAL CONDUCTOR Birger W.Nordiander, Schenectady, and John A.

Loritsch, Scotia, N. Y., assignors to General Electric Compa-ny, acorporation of New York Application June 13, 1945, Serial No. 599,164 sclaim. (ci. 174-'-121) 1 2 This invention relates to the production ofelecv, HQ 0 0H trical coils and other articles comprising metalliccopper or a copper alloy. More particularly the /C\ /O\ invention isconcerned with the production of HIC CH. Hao CH: articles having, incombination, (1) a metal of 5 me H, me H, the class consisting of copperand its alloys and C C/ (2) a polymeric material, e. g., a DOlymerZed H,H, composition comprising a polymerized unsatnu(hydroxycyclohexyl)peroxide i,1,

urated alkyd resin. Specifically, the articles of VI our invention areproduced by a method which involves polymerizing, in contact with ametal of the aforementioned class, a polymerizable composition which,when benzoyl peroxide or its equivalent is rincorporated therein,attacks the aforesaid metal due to the said peroxide contDi.(tert1arybuty1pei-phthalate) tained therein, causing retardation orinhibition VH o of polymerization, said composition having incorporatedtherein as an accelerator of polymeriza- Q OWCH' tion a compo-und of theclass consisting of sec- Hz), ondary-butyl hydroperoxide, tertiary-butylhy- O O C(CH,), droperoxide, tertiary-amyl hydroperoxide, 1-hy Ildroxycyclohexyl hydroperoxidel, 1,1'di hy o s droxycyclohexyl) peroxide1*,1, di (tertiary- D-(tertiary`buty1persuccmate) C-O-O-C (CHI):

butyl perphthalate), di-(tertiary-butyl persuc- VIH l 0 cinate),di-(tertiary-butyl peradipate), tertiary- -o-o-owm). butyl perfuroate,di-(methyl maleoyl) kperoxide Hm and low-molecular-weight polymers (e.g., dimers,

trimers, tetramers, pentamers, hexamers. etc.) of -0 0.C(CH)" di-(methyl maleoyl) peroxide. Polymerization 0 preferably is effected underheat, e. g., at a tem- DMrtiaI-Tbutylperadpate) perature Within therange of 60 to 130 C. f IX HC CH 0 The formulas for the aforementionedmonomeric compounds are shown below: H 0000 (CEM H I 3 5 Tertiary-butylperfuroate CB1-CHP I -O-O-H f o CH: Secondarybutyl hydroperoxide C--OCH' n H,c\ f ibo Hic-o-o-o-H X o o n.0 H/ Tertiary-butyl hydroperoxideHg. c 0 CH m mo l H,C C 0. 0..H Di- (methyl maleoyl) peroxide y HIC ySecondary-butyl hydroperoxide, tertiary-butyl Hl hydroperoxide,tertiary-amyl hydroperoxide, 1- v 50 hydroxycyclohexyl hydroperoxide-land cli-(terh d 1d Tertiary amyl y roperox e tiary-butyl perphthalate)are available on the Iv no o o-H open market. D-(tertiary-butylpersuccinate), \C/ di-(tertiary-butyl peradipate) and tertiary-butylperfuroate are prepared, for example, by effecting B2C CH 55 reactionbetween the corresponding acid chloride H, H, and an alkaline-earthmetal salt, e. g., the barium C salt, of tertiary-butyl hydroperoxide.1,1di

H. i (lrydroxycyclohexyl) peroxide-1,1 is produced1hydroxyeyc1ohexy1nydroperoxide.1 by effecting reaction, in anhydroustertiary-butyl alcohol, between cyclohexanone and hydrogen peroxide inthe ratio of tw'o mols of the former to one mol of the latter. Afterstanding for several days at room temperature or thereabouts theanhydrous alcohol and other volatile matter are removed under reducedpressure, yielding an oily material having an active oxygen contentcorresponding tothat calculated for l,1'-di(hydroxy cyclohexyl)peroxide-1,1'. The particular grade of di-(methyl maleoyl) peroxide usedin our tests was obtained from Buffalo Electro-Chemical Company, Inc.,Buialo, N. Y., as Organic Peroxide No. 1453. It probably contained bothmonomeric di-(methyl maleoyl) peroxide and lowmolecular-Weight polymersthereof, examples of which have been given.

A specific embodiment of our invention is an electrical device includingan electrical coil comprising windings of a copper conductor, solidpermeable insulation adjacent said conductor, said insulation beingimpregnated with an impregnant which is in contact with at least aportion of said conductor and which comprises 'the product ofpolymerization, more particularly the solid product of polymerization,of the polymerizable, hardenable composition deilned in the ilrstparagraph of this specification.

In the accompanying drawing Fig. 1 represents a cross-sectional view ofa member composed of copper or copper alloy surrounded by, and incontact with, a solid product of polymerization of a polymerizablecomposition of the kind hereinbefore described with reference to ourinvention. Fig. 2 shows in cross-section a member composed of copper orcopper alloy and permeable insulation, e. g., asbestos, glass fibers,cotton, etc., in thread, felted, woven or other form, upon said member,said insulation being impregnated with an irnpregnant which -is incontact with at least a portion of said member andwhich comprises asolid product of polymerization of .a polymerizable composition of thekind with which our invention is concerned.

Electrical devices including electrical coils in which combinations suchas shown, for instance, in Fig. 2 advantageously are used, areillustrated in the drawings accompanying Nordlander, I oritsch andBachli copending application Serial,

No. 509,366, filed November 8, 1943, assigned to the same assignee asthe present invention and now abandoned. i.

4 those formed of cotton, glass, asbestos, silk, nylon, celluloseacetate and other cellulose esters, ethyl cellulose and other celluloseethers, etc.

solventless varnishes" include polymerizable systems of a relatively lowvapor pressure, for example polymerizable unsaturated alkyd resinscomprising polymerizable esters o! a polyhydric alcohol (or a pluralityof polyhydric alhols) and an alpha-unsaturated alpha,betapolycar boxylicacid (or a plurality oi polycarboxylic acids, at least one of which isan alpha-unsaturated alpha,betapolycarboxylic acid); polymerizableesters of an unsaturated monohydric alcohol, e. g., allyl alcohol, andan organic polybasic acid, e. g., a saturated or unsaturated aliphaticpolycarboxylic acid, an aromatic polycarboxylic acid, a chlorinated orother halogenaied aromatic polycarboxylic acid, an inorganic polybasicacid, e. g., phosphoric acid, etc.; polymerizable mixed esters ofunsaturated monohydric alcoholsy and polybasic acids; polymerizablemixed esters of a polybasic acid and a plurality of alcohols, one ofwhich is an unsaturated monoi hydric alcohol and another of which is apoly- It. is known that copper salts exert a pronounced eil'ect on thepolymerization of unsaturated compounds and that, depending upon theirconcentration, they may retard or completely inhibit the polymerizationwhich otherwise readily would take place. Sometimes advantage is takenof this property, for example in the stabilization of certain unstablematerials during storage, distillatiometc. On the other hand, thiseffect may prove extremely troublesome when it becomes necessary tocarry out polymerization in the presence of copper, such as whenpolymerization is eiected in forming the insulation of electricalequipment where this metal is commonly present.

The polymerization of polymerizable compositions in contact with copperheretofore has been a considerable problem, especially in utilizingpolymerizable materials of the class sometimes referredto as solventlessvarnishes in structures containing copper or alloys thereof, either bareor covered with untreated, permeable materials, e. g., yarns and fabricssuch as hydric alcohol; and mixtures o! the aforementioned polymerizableesters. In the utilization of such polymerizable materials a smallamount (e. g., 0.5 to 5% by weight) oi' a compound acting as aneffective polymerization catalyst,`

usually benzoyl peroxide, is added to the polymerizable composition, andthe mixture is heated at, for instance, -100 C. or theres-bouts.Ordinarily, in due course of time, there is obtained a clear,water-white or light-colored prod- P uct having high heat, moisture,acid and alkali resistance, outstanding mechanical and dielectricproperties, and which contains little or none of thelow-molecular-weight starting component or components,

When polymerizable compositions such as` aforementioned are polymerizedwith the aid of benzoyl peroxide o r equivalent material in the absenceof copper or copper alloy, no diiiiculties ordinarily are encountered.However, when attempts are made to carry out the polymerization in thepresence of metallic copper, or one of its alloys. the result isentirely diilerent. An intense greenish-blue coloration soon developsaround the copper surface, which coloration in extreme cases, at highratio of copper surface to volume of varnish innormally-slow-polymerizing systems, may spread throughout the entiremass. Furthermore, instead of polymerization of the varnish into a hardsolid having the aforementioned desirable properties being effected, asoft, jelly-like, crumbly material is formed around .the copper wherethe coloration has appeared. Under the conditions which cause a greencoloration to form throughout the mass, a complete inhibition ofpolymerization may occur. Since a large aggregate surface of copper isexposed to a relatively small amount of varnish in most electricalequipment where the conductors are to be provided with adequateinsulation by an appropriate varnish treatment, for exam- =ple inelectrical coils, complete failure often is experienced when attemptsare made to -use varnishes of the above-described type in suchapplications. The varnish either will not polymerize at all or willconvert only partially into a polymeric material, the mechanical anddielectric properties of which are unsatisfactory. The results ofExamples 1, 2 and 3 more fully bring out these facts.v

Example 1 A bundle of copper wire. consisting of 40 strands of wire of80 mils diameter with an aggregate surface of about 160 squarecentimeters, was placed in a tightly itting Pyrex test tube holdinggrams of a varnish composed of, by weight, two parts of diallylphthalate, one part of dlethylene glycol maleate having an acid numberof 60, and benzoyl peroxide in an amount corresponding t.) 0.5% byweight of the aforementioned components.

The bundle was completely immersed in the varnish, being separated fromthe bottom of the tube as well as covered on top with a onecentimeterlayer of varnish. The tube was kept for 24 hours at 80 C. During thisperiod excemive greening developed adjacent to the sur- ,face of thewires, and in these areas the varnish was converted into a very soft,cheesy gel having no mechanical strength. Further heating for 145 hoursat 80 C. did not cause any improvement in the character of thismaterial. It was noted that while the layer of varnish `over the top ofthe bundle of wires did not discolor during the heating. nevertheless itwas converted into a rather inferior, crumbly mass. In marked contrast,a sample of the same composition kept for 24 hours at 80 C. in theabsence of the copper wires yielded a polymeric material that was veryhard, rigid and tough throughout.

Numerous otherk tests in which the ratio of components, theconcentration of benzoyl peroxide catalyst and the temperature werevaried likewise gave similar unsatisfactory results when attempts weremade to effect polymerization in the presence of copper. For a givenslowlypolymerizing varnish the effect was more proimmediate or durablevalue. It also was found that while little or no greening might benoticeable upon close examination. the polymerized material next to thecopper nevertheless was rather soft, causing the wires to be very poorlybonded together. Good bonding is important, of course, in order toprevent movement of conductors and consequent abrasion of insulationresulting from magnetic and mechanical vibration. Another disadvantageresulting from `not being able to obtain, in a practical way, completelypolymerized products lies in the much higher dielectric loss factor,especially at high temperatures, which the incompletely polymerizedproducts exhibit as compared with the corresponding, thoroughlypolymerized materials.

The complete inhibition by copper of the polymerization of diallylphthalate of negligible acid value, catalyzed by benzoyl peroxide,showed that the acidity of the polymerirable composition had little orno bearing on this phenomenon, as is evidenced by the results of Example2.

nounced the higher the temperature. However. f

if the varnish was made to polymerize fairly rapidly, the greening andthe inhibitation effect were less noticeable. Thus. at a giventemperature, the higher the concentration of benzoyl peroxide (above acertain limiting value) the less visible was the attack on the cooper.This is understandable, since the shorter the time the polymerizablematerial remains liquid, the less is the attack on the copper and,consequently, the lower the concentration of copper salts in solution.As is shown by the results of Example 3, the retarding effect increasesrapidly with an increase in the concentration of the copper in solution.complete inhibition of polymerization being effected by the presence ofavery minute amount of copper. However, the control of the polymerizationreaction, which is strongly exothermic, becomes more diillcult thehigher the catalyst concentration. When large thicknesses of materialare to be formed by polymerization, it is essential that a slowpolymerization rate be malntained. Otherwise the heat of polymerizationmay accumulate in the interior, causing variations in the rate ofpolymerization and hence unequal shrinkage throughout the mass withresulting formation of internal stresses in the product, which stresseseventually may be released by cracking of the mass thereby producing amaterialhaving little or no commercial value.

For these reasons we found it to 'be entirely impractical to reduce thecopper ypoisoning effect suiiiciently by merely speeding up the rate ofpolymerization, e. g., by using a larger amount of benzoyl peroxidecatalyst. Attempts in this direction invariably led to products thateither were cracked or were too strained to have any Example 2 Onesingle strand of an'80-mil-diameter copper wire was placed in a Pyrextest tube with 10 grams of diallyl phthalate (acid value less than one)containing-1% by weight of benzoyl peroxide. The sample was heated for90 hours at C. The liquid soon assumed an intensely green color andstill remained fluid at the end of the heating period. On the otherhand, a similar sample of diallyl phthalate kept at 80 C. in the absenceof copper wire gelled inabout 8 hours and was almost completelypolymerized at the end of 50 hours, forming a very hard. tough, clearproduct containing, by weight, only 5% of acetone-extractable matter.

As shown by the results of Example 3, even very small traces of coppersalts have a pronounced effect on the polymerization of polymerizablecompounds of the kind aforementioned.

Example 3 The copper salt used was in the form of a blue solutionobtained by heating diallyl phthalate containing benzoyl peroxide in thepresence of freshly reduced copper turnings. Before use this solution,after having been decanted from the turnings, was 4heated to 170 C. todestroy the excess of benzoyl peroxide present. The copper content wasthen carefully determined and found to be 0.0004 gm. Cu per gm. ofsolution (or, by weight, 400 parts Cu per million parts of solution).Using this material. solutions of diallyl phthalate with 2% (by weight)added benzoyl peroxide and varying copper content were made up. Thesesolutions were heated at 80 C. for 15 hours. The results are shownbelow:

Copper- Sample No. (frtnf Nature of Product Million 0 Hard, tough.. 1Do. 5 Rubbery, short. l0 Very soit gel. 50 Semi-fluid gol. lill Veryviscous syrup. all Viscous syrup. 400 Fluid syrup.

As will be noted from the foregoing results, Athe presence of only 5millionth of a gram of copper per gram of solution is very pronounced,the prod- 7 uct being entirely diilerent nom the one whichnormallyresults. Itsisomlybementlonedthst Sample No. 8 did not gel evenafter heating for an additional 144 hours at 80 C.

The speciilc nature ot the peroxides of the class with which thisinvention is concerned as eilective agents for accelerating thepolymerizatlon of polymerizable compositions in the presence of copperor an alloy thereof is shown by the results of tests in which thefollowing peroxidcs were used:

Acetyl peroxide Caprylyl peroxide Pelargonyl peroxide Lauroyl peroxideStearoyl peroxide 3,4-dichlorobenzoyl peroxide Diheptanol peroxideDi-[phenyl-(hydroxy) -methyll peroxide Urea hydrogen peroxide Dibenzaldiperoxide Di-(tetiary-butyl) peroxide Tertiary-butyl perbenmate Eachperoxide was incorporated to the extent of 1% by weight in 10 grams o! avarnish composed of equal paris by weight of diallyl phthalate anddiethylene glycol maleate. A coil of bare copperwire,havinganexposedsurfaceotabout80 square centimeters, was immersed inthe varnish. Two samples of each combination were heated for 48 hours,one at 60 C. and the other at 100 C. Although the attack on the copperand the retardation or inhibition of the polymerization of the varnishwere more pronounced in some cases than in others, the results inall-cases were such as to make it impractical to use any of theperoxides tested as polymerization catalysts in the presence of barecopper.

Example 4 Example 1 was repeated, only with the diilerence that 1% byweight of a 60% solution of tertiary-butyl hydroperoxide intertiary-butyl alcohol was vused asa catalyst instead of benzoylperoxide; also, because of the low activity of tertiary-butylhydroperoxide at lower temperatures, the sample was heated at 110 C.instead of at 80 C. as in Example l. Gelation occurred within 2 hours.After heating for 24 hours the sample was found upon examination to haveconverted throughout into a solid, tough material that showed no tracewhatsoever of discoloration or o! attack upon the copper. When cut openthe polymex-ized material proved to adhere very` tenaciously to thecopper. No diiierence could be noted in the quality of the polymeri'sedmaterial when compared with a sample of the same varnish polymerzed forthe same length of time at the same temperature in the absence ofcopper.

Example 5 Abundleofcopperwirewmilsindiameterhavingatotalareaofabmitwsquarecentimeters and weighing about grams, wasimmersed as described under Example 1 in 10 grams of a varnish composedof, by weight, two parts of diallyl phthalate, one part of diethyleneglycol maleate having an acidnumber of 60, and a 60% solution oftertiary-any1 hydroperoxide (in tertiary-amyl alcohol) in an amount dingto 1% by weight of the aforementioned componen. The sample was heatedfor hours at 8 bondedtothemetalr'csmted.Thenwercnovisiblediscolorationorotherevidencethattbecopperhadbeenattacked.Thephysicalcharacteristics of the copolymer matched those o! theproductobtainedwhenthesamevarnishwas polymerlxed under the sameconditions in the absenceoithebundleofcopperwirc.

Example Acoilwoundirombarecopperwiremilsindiameterandhavingatotalareaolabmxtl)squarecentimcterswascmnpletelyimmerledasdescribedunderlxampleliniogramsota varnishwhichwasthesamcaathevarnisho(Examplei except that itcontainedll o( 141!- droxycyclohexylhydroperoxide-1 insteadof 0.5% of bensoyl peroxide. The polymericmaterial showednogreeningorotherevidencethatthe copperhadbeenattacked.Thepolymerhedvar- Esample 7 Abundleofcopperwirehavingatotalareao! about40 square centimeters was completelyimmersedasdescribedinkxamplcliniograms of diallyl phthalate into whichhad been dissolved 1% by weight thereof of 1,1'di(hydroxy cyclohexyl)peroxide-1,1'. The sample was heated for 48hours at 100 C.Therewasnoevidencc of corrosion or inhibition, and the resulting polymerwas a hard, tough solid.

Example l A varnish prepared from 20 grams of diallyl phthalate, 20grams of dicthylene glycol maleate havinganacidvalueofwandonegramota 38%solution of secondary-butyl hydroperoxide (in secondary-butyl alcohol)was placed in a test tube containing a bundle of -mi1 diameter, barecopperwirehavingatotalareaofaboutwsquarc centimeters. `'Ihe bundle ofwire was completely covered with the varnish. The sample 'was heated for24 hours at 100 C. There was no evidence of copper discoloration, andthe copolymer that formedwashard,toughandwellbondedtothe copper surface.Y

vEixample 9 Example 1a Same asExample9 wlththeexceptionthatthe varnishcontained 0.1 gram of di-(methyl maleoyl) peroxide instead of 0.1 gramof di-(tertlarybutyl perphthalate) and the heating period was 15 hoursat 60 C. followed by heating for 24 hoursatC. 'I'herewasnotraceoioopperdiscoloration or of inhibition of polymerizationinthearcasadjaccnttothebareeower.

Example 11 Thisexampleshowstheresnltsobtaincdwhen the followingperoxides were added to diallyl C. Ahard,to hproductthatwasnrmly 1sphthalakandthemixturethmallowedtoatand in contact with copper forvarying periods of time:

Tertiary-butyl hydroperoxide tertiary-butyl alcohol) Tertiary-amy]hydroperoxide (60% solution in tertiary-amylalcohol) n1hydroxycyclohexyl hydroperoxide-1 Di- (tertiary-butyl perphthalate) Di-(methyl maleoyl) peroxide (60% solution in Peroxide Used i ObservationNo greening in l week, after which time no further observations weremade.

N o greening in l month, after which time no further observations we'emade.

No discoloration of any yirind after months standing.

No discoloi ation of any kind altere months standing.

No discoloration after 20 months standing, and no inhibiting action onthe polymerization characteristics o! tbe sample at elevatedtemperatures.

Di-(tertiary-butyl perphthalate) l,ldi(hydroxycyclohexyl) peroxide-1.1'.

1hydroxycyclohexyi hydroperoxide-1 Tertiary-amy] hydroperoxide.

Tertiary-butyl hydroperoxide When diallyl phthalate containing benzoylperoxide, dibenzal diperoxide, acetyl peroxide, caprylyl peroxide,pelargonyl peroxide, lauroyl peroxide, stearoyl peroxide andtertiary-butyl perbenzoate was similarly tested, greening was notedaround the copper or throughout the entire mass 4o in from 2 to 15hours, showing that the copper had been attacked. This isfurther'evidence of the speciilc nature of the peroxides used inpracticing the present invention.

Example 12 One-tenth gram oi benzoyl peroxide was added to 10 grams ofbutyl methacrylate. The resulting composition was hea-ted at 60 O. in atest tube containing one strand of bare copper wire 80 mils in diameterand having an area oi' about 8 square centimeters. The wire wascompletely immersed in the liquid butyl methacrylate. 'Ihe sample wasstill iluid after heating for 15 hours, and its intense blue-green colorindicated that extensive corrosion of the copper hadtaken place. I I'hisexample shows that the unsuitability of benzoyl peroxide as a catalystfor accelerating the polymerization of polymerizable compounds in thepresence of copper is not limited to the specific polymerizablecompounds hereinbefore mentioned, but is equally true of esters ofunsaturated monocarboxyllc acids and other monomers.

Example 13 A bundle of 80-mi1 (diameter) copper wire, having a totalarea of about 40 square centimeters, was immersed completely in 10 gramsbutyl methacrylate having dissolved therein 1% `by weight of1,1'-di-(hydroxycyclohexyl) peroxide-1,1 (70% active strength). Thesample was heated for 40 hours at 80 C. There was no discoloration orother evidencey of coppery poisoning. The clear, water-white polymerthat formed 76 a tough copolymer was was hard and brittle at roomtemperature and adhered tightly the copper wire;

Example 14 A bundle of copper wire such as described ln Example 13 wascovered with styrene into which had been dissolvedl 1% by weight of a60% solution oi' tertiary-butyl hydroperoxide in tertiarybutyl alcohol.The sample was heated for 15 hours at C. and thereafter for 5 hoursat100 C. There was no discoloration or other evidence oi' coppercorrosion. As in the preceding example, the resulting clear, water-whitepolymer was hard and brittle at room temperature, and adhered well tothe copper,

Example 15 A coil of bare copper wire 80 mils in diameter and having asurface area of 16 square centimeters was completely immersed in avarnish comprising 5 grams diallyl phthalate, 5 grama diethylene glycolmaleate (acid value 50) and 0.1 gram di- (tertiary-butyl persuccinate).Ihe sample was heated at C. for 24 hours. 'I'here was no trace of copperdiscoloration and a hard, formed.

Example 16 Same as in Example 15 with the exception that ther varnishcontained 0.1 gram di-(tertiary-butyl peradipate) instead ofdi-(tertiary-butyl persuccinate). As in the preceding example, theresulting copolymer was hard and tough, and showed no trace of copperdiscloration.

Example 17 v Same as in Example 15 with the exception that the varnishcontained 0.1 gram tertiary-butyl perfuroate in place oidi-(tertiary-butyl persuccinate). The resulting copolymer had the samecharacteristics asVV the products of Examples 15 and 16.

Example 18 hard, tough copolymer with no trace of copper I discolorationor inhibition.

Example 19 Same as in Example 18 except that a coil of brass wire 39mils in diameter and having a surface area oi' 29 square centimeters wasused and 0.1 part tertiary-butyl pe'rfuroate was employed instead of 0.1part ldi-(tertiary-butyl perphthalate). As in the preceding example. theresulting copolymer was hard and tough, and showed no trace of copperdiscloration or inhibition.

It will be noted that in allof the 'foregoing examples the metal (copperor alloy thereof) was completely immersed in the polymerizablecomposition.

As evidence of the fact that the action of the peroxide is independentof the medium employed, the following examples are given:

Example 20 11 peroxide in tolueneu The sample was heated for 20 hours at80 C. during which time an intensely blue-green color developed and ablue deposit formed. The latter was filtered oil, washed, dried andanalyzed. The copper content agreed with that calculated for cupricbenzoate.

Example 21 Copper pellets weighing grams were placed in a test tubecontaining toluene in which was dissolved by Weight of a 60% solution oftertiary-butyl hydroperoxide in tertiary-butyl alcohol. The sample washeated for 20 hours at 100 C. The liquid was not discolored and therewere noV visible signs that the copper pellets had been attacked at theend of this period of time.

It will be understood, of course, by those skilled in the art that theforegoing examples are given merely by way of illustration and not byway of limitation. Thus, instead of copper specifically mentioned inmost of the examples, similar results are obtained when thepolymerization is effected in the presence of an alloy of copper, e. g.,

brass, bronze, etc., as evidenced by the results of Examples 18 and 19.Likewise it will be understood that the invention is applicable to thepolymerization of polymerizable compounds in the presence of copper or acopper alloy regardless of the form of the latter. For example, thecopper or copper alloy may be in wire form or it may be in sheet, rod,tube, bar, electroplated (in the case of copper) or other form.

Other and more specific examples of polymerizable compositions that maybe used in practicing our invention are esters containing ethylenic oracetylenic unsaturation in either the alcohol radical or the acidradical, or in both, e. g., saturated and unsaturated alcohol esters ofunsaturated monocarboxylic and polycarboxylic acid, unsaturated alcoholesters of non-ethylenic (e. g., aromatic and saturated aliphatic)polycarboxylic acids, unsaturated alcohol esters of saturatedmonocarboxylic acids, etc. Thus, the polymerizable compositions may be,for instance, unsaturated alcohol esters, e. g., the vinyl, allyl,methallyl, crotyl, propargyl, l-chloroallyl, 2-chloroallyl, cinnamyl,etc., esters of saturated and unsaturated, aliphatic and aromatic,monobasic and polybasic acids such, for instance, as acetic, propionic,butyric, valerio, caproic, acrylic, alkacrylic (e. g., methacrylic,ethacrylic, etc.), crotonic, oxalic, malonic, succinic, glutaric,adipic, pimelic, suberic, azelaic, sebacic, maleic, fumaric, citraconic,mesaconic, itaconic, aconitic, benzoic, toluic, phthalic, chlorinated orother halogenated phthalic, terephthalic, isophthalic, benzoyl phthalic,cinnamic, etc.; the saturated alcohol esters, e, g., the methyl, ethyl,propyl, butyl, isobutyl, ethylene glycol, glycerol, pentaerythritol,etc., esters of the unsaturated aliphatic monobasic and polybasic acids,illustrative examples of which acids appear above; vinyl cycliccompounds, e. g., vinyl naphthalene, vinyl furane, divinyl benzene,etc.; unsaturated ethers, e. g., diallyl ether, etc.; unsaturatedketones, e. g., divinyl ketone, methyl vinyl ketone, etc.; methylenemalonic esters, e. g., methylene dimethyl malonate, methylene diethylmalonate, etc.; polymerizable unsaturated alkyd resins, both modifiedand unmodified, e. g., ethylene glycol maleate, diethylene glycolfumarate, propylene glycol itaconate, glyceryl maleate, diethyleneglycol fumarate phthalate, ethylene glycol maleate succinate, aceticacidmodified ethylene glycol maleate, octyl alcoholmodified diethyleneglycol fumarate,numerous 12 other examples appearing, for example, inNordlander copending applicationsSerial Nos. 302,165 and 302,166, illedOctober 3l, 1939, both now abandoned, in D'Alelio copending applicationsSerial Nos. 302,167, 302,168 and 302,174, also illed October 31, 1939,and now Patents Nos. 2,407,479, 2,428,787 and 2,428,788 respectively,and in DAlelio Patents 2,260,005, 2,288,315, 2,308,494, 2,308,495,2,309,798 and 2,323,706; allyl esters, e. g., allyl acrylate, allylmethacrylate, diallyl maleate, diallyl itaconate, diallyl fumarate,triallyl aconitate, triallyl tricarballylate, triallyl phosphate, etc.,numerous other examples of these and other polymerizable compounds beinggiven in the aforementioned Nordlander and DAlelio applications andpatents; and homogeneous mixtures of the compounds (as broadly andspecincally mentioned) hereinbefore set forth and others given in theabove-identified applications and patents. l

We prefer to use polymerizable compounds or compositions containing oneor more (more particularly two, three, four or more) CH2=C groupings,numerous examples of which materials have been given herein. Where thecombination of polymerized material and copper or alloy thereof may besubjected to an elevated temperature (e. g., C. or above) during serviceuse, it also generally is preferable to use a polymerizable compositionthat can be polymerized to a substantially infusible state.Polymerizable materials that can be polymerized to a state wherein theyare not only infusible but also substantially insoluble in the ordinarysolvents and chemicals are particularly useful in many applications. y

The amount of peroxide which is incorporated in the polymerizablecomposition may be varied considerably, but generally will be within therange of 0.2% to 4 or 5% by weight by the polymerizable material withwhich it is incorporated.,

Good results have been obtained when the peroxide is employed in anamount corresponding to from 0.5 to 1.5% by weight of the polymerizablecomposition.

Polymerization of the polymerizable composition may be effected attemperatures ranging, for example, from room temperature (20 to 30 C.)to temperatures above C., for example about C., but ordinarily we usetemperatures within the range of 60 to 120 C. in causing thepolymerizable compound or homogeneous mixture of compounds topolymerize.

The present invention is particularly useful in the production ofelectrical coils where it obviates the diiilculties heretoforeencountered in effecting satisfactory polymerization of polymerizablecoil impregnants in contact with copper conductors exposed to the actionof the varnish, e. g., copper wires having permeable insulation such aspaper, cotton cloth, etc., adjacent the wires. However, the inventionalso may be used in making switch-board panels, housings for variouselectrical devices, etc., in insulating coils and other parts oftransformers, in fabricating decorative, household and industrialarticles wherein a polymerizable compound is cast around an ,insert ofcopper or an alloy thereof, and in numerous other applications.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. An article of manufacture comprising a metal selected from the classconsisting of copper and alloys of copper surrounded at least in part 75by and in direct contact with a solidpolymer free 13 of discolorationand free of evidence of retardation of polymerization, said polymercomprising the product of polymerization of a mixture of ingredientscomprising (a) a polymerizable organic ester containing a polymerizablegrouping selected from the class consisting of the CH2=C grouping andthe CH=CH grouping of an alpha unsaturated alpha beta polycarboxylicacid, and (b) an accelerator of polymerization comprising a compoundselected from the class consisting of secondary-butyl hydroperoxide,terilary-butyl hydroperoxide, tertiary-amyl hydroperoxide,l-hydroxycyclohexyl hydroperoxide-1,

1,1 '-di (hydroxycyclohexyl) peroxide-1,1", ditertiary-butylperphthalate), di- (tertiary-butyl persuccinate), di-(tertiary-butylperadipate), tertiary-butyl perfuroate, di-(methyl maleoyl) peroxide andlow-molecular-weight polymers of di- (methyl maleoyl) peroxide, theaforementioned accelerators of polymerization being capable ofpolymerizing the polymerizable composition without retardation ofpolymerization and without discoloration of the polymerizable materialas a result of the direct contact of the latter with the metal of theaforementioned class.

2. An article of manufacture comprising a metal selected from the classconsisting of copper and alloys of copper having a solid porous coveringupon said metal, the metal and porous coating being surrounded at leastin part by and in direct contact with a solid polymer free ofdiscoloration and free of evidence of retardation of polymerization,said polymer comprising the product of polymerization of a mixture ofingradients comprising (a) a polymerizable organic ester containing apolymerizable grouping selected from the class consisting of the CH2=Cgrouping and the -CHr-CH- grouping of an alpha unsaturated alpha betapolycarboxylic acid, and (b) fan accelerator of polymerizationcomprising a compound selected from the class consisting ofsecondary-butyl hydroperoxide. tertiary-butyl hydroperoxide,tertiary-amyl hydroperoxide. l-hydroxycyclohexyl hydroperoxide-1,1,1f-di-(hydroxycyclohexyl) peroxide-1,1', di- (tertiary-butylperphthalate), di- (tertiary-butyl peradipate),tertiary-butylperfuroate, di-(methyl maleoyl) peroxide andlow-molecular-Weight polymers of di- (methyl maleoyl) peroxide, theaforementioned accelerators of polymerization being capable ofpolymerizing the polymerizable composition without retardation ofpolymerization and without discoloration of the polymerizable materialas a result of direct contact of the latter with the metal of theaforementioned class. 3. An article of manufacture comprising coppersurrounded at least in part by and in direct contact with a solidpolymer free of discoloration and free of evidence of retardation andpolymerization, said polymer comprising the product of polymerization ofa mixture of ingredients comprising (a) a heat-polymerizable unsaturatedalkyd resin and (b) a small amount of tertiarybutyl hydroperoxide as anaccelerator of polymerization, the said accelerator being capable ofpolymerizing the polymerizable composition Without retardation ofpolymerization and without discoloration of the polymerizable materialas a result of the direct contact of the latter with the copper. f

a. 4. An article of manufacture comprising copper surrounded at least inpart by and in direct contact with a solid polymer free of discolorationand free of evidence of retardation of polymeri- 14 zation, said polymercomprising the product of polymerization of a mixture of ingredientscomprising (a) a heat-polymerizable unsaturated a1- kyd resin and (b) asmall amount of tertiary- 5 butyl perfuroate as an accelerator ofpolymerization, the aforementioned accelerator being capable ofpolymerizing the polymerizable composition without retardation ofpolymerization and without discoloration of the polymerizable materialas the result of the direct contact of the latter with the copper.

5. An article of manufacture comprising copper surrounded at least inpart by and in direct contact with a solid polymer free of discolorationand free of evidence of retardation of polymerization, said polymercomprising the product of polymerization of a mixture of ingredientscomprising (a) a heat-polymerizable unsaturated alkyd f A`resin and (b)a small amount of di-(tertiary-butyl perphthalate) as an accelerator ofpolymerization, the aforementioned accelerator being capable `ofpolymerizing the polymerizable composition without retardation ofpolymerization and without discoloration of the polymerizable materialas a result of the direct contact of the latter with the copper. J

6. The method which comprises polymerizing in contact with a metalselected from the class consisting of copper and alloys of copper, apolymerizable organic ester contacting and surrounding at least in partthe aforesaid metal and containing a polymerizable grouping selectedfrom the class consisting of the CH2=C grouping and the -CHzCH- groupingof an alpha unsaturated alpha beta polycarboxylic acid and havingincorporated therein as an accelerator oi' polymerization a compoundselected from the class consisting of secondary-butyl hydroperoxide,tertiary-butyl hydroperoxide, tertiary-amyl 40 hydroperoxide,l-hydroxycyclohexyl hydroperoxide-l, 1,1di-(hydroxycyclohexyl)peroxide-1,1', di- (tertiary-butyl perphthalate) di( tertiarybutylpersuccinate), di-(tertiary-butyl peradipate), tertiary-butylperfuroate, di-(methyl maleoyl) peroxide and low-molecular-Weightpolymers of di-(methyl maleoyl) peroxide, the aforementionedaccelerators being capable of polymerizing the polymerizable compositionwithout retardation of polymerization and Without discoloration of thepolymerizable material as a, result of the contact of the latter withthe metal of the aforementioned class.

7. An article of manufacture comprising copper surrounded at least inpart by and in direct contact with a solid polymer free of discolorationand free of evidence of retardation of polymerization, said polymercomprising the product of polymerization of a` mixture of ingredientscomprising (a) a heat-polymerizable composition comprising diethyleneglycol maleate and diallyl phthalate and (b) a small amount oftertiary-butyl hydroperoxide as an accelerator of polymerization, saidaccelerator being capable of polymerizing the polymerizable compositionWithout retardation of polymerization and without discoloration of thepolymerizable material as a result of the direct contact of the latterwith the copper.

8. The method which comprises polymerizing,

in contact with copper and at a temperature within the range of 60 to130 C., a heat-polymerizable composition comprising a polymerizableunsaturated alkyd resin having incorporated therein as an accelerator ofpolymerization a compound of the class defined in claim 6, said 15 l 10accelerator being capable of polymerizins the "UNITED STATES PATENTS-polymerizable composition without retardation Number Name Date ofpolymerization and without discoloration of 961805 scott June 21 1910the polymerzable material as a result of the 12132126 Baekea Jan 23'1917 Contact of the latter with the copper. f 5 211473124 webb -.11'.Feb'. 21, 1939 BIRGER W- NORDLANDER 2,172,445 Lutz "sept, 12, 1939 JOHNA LORTTSCH 2,191,581 Novak et a1 Feb. 27, 1940 2,340,109 DAlelio Jan.25, 1944 REFERENCES CITED 2,367,805 semple 31111.23. 1945 The fouowingreferences are of record in the l0 2,379,978 Meyer July 1o, 1945 file ofthis patent: 2,391,920 Peterson Jan. 1, 1946 2,443,736 Kropa June 22,1948

2. ARTICLE OF MANUFACTURE COMPRISING A METAL SELECTED FROM THE CLASSCONSISTING OF COPPER AND ALLOYS OF COPPER HAVING A SOLID POROUS COVERINGUPON SAID METAL, THE METAL AND POROUS COATING BEING SURROUNDED AT LEASTIN PART BY AND IN DIRECT CONTACT WITH A SOLID POLYMER FREE OFDISCOLORATION AND FREE OF EVIDENCE OF RETARDATION OF POLYMERIZATION,SAID POLYMER COMPRISING THE PRODUCT OF POLYMERIZATION OF A MIXTURE OFINGREDIENTS COMPRISING (A) A POLYMERIZABLE ORGANIC ESTER CONTAINING APOLYMERIZABLE GROUPING SELECTED FROM THE CLASS CONSISTING OF THE CH2=C<GROUPING AND THE -CH=CH- GROUPING OF AN ALPHA UNSATURATED ALPHA BETAPOLYCARBOXYLIC ACID, AND (B) AN ACCELERATOR OF POLYMERIZATION COMPRISINGA COMPOUND SELECTED FROM THE CLASS CONSISTING OF SECONDARY-BUTYLHYDROPEROXIDE, TERTIARY-BUTYL HYDROPEROXIDE, TERTIARY-AMYLHYDROPEROXIDE, 1-HYDROXYCYCLOHEXYL HYDROPEROXIDE-1,1,1''-DI-(HYDROXYCYCLOHEXYL) PEROXIDE-1,1'', DI(TERTIARY-BUTYLPERPHTHALATE), DI-(TERTIARY-BUTYL PERADIPATE), TERTIARY-BUTYLPERFUROATE,DI-(METHYL MALEOYL) PEROXIDE AND LOW-MOLECULAR-WEIGHT POLYMERS OFDI-(METHYL MALEOYL) PEROXIDE, THE AFOREMENTIONED ACCELERATORS OFPOLYMERIZATION BEING CAPABLE OF POLYMERIZING THE POLYMERIZABLECOMPOSITION WITHOUT RETARDATION OF POLYMERIZATION AND WITHOUTDISCOLORATION OF THE POLYERMIZABLE MATERIAL AS A RESULT OF DIRECTCONTACT OF THE LATTER WITH THE METAL OF THE AFOREMENTIONED CLASS.